Agrawal Lokesh, Vanhorn-Ali Zainab, Alkhatib Ghalib
Department of Microbiology and Immunology and Walther Oncology Center, Indiana University School of Medicine, Indianapolis 46202, USA.
J Leukoc Biol. 2002 Nov;72(5):1063-74.
Although a number of chemokine receptors display coreceptor activities in vitro, chemokine receptor 5 (CCR5) and CXC chemokine receptor 4 (CXCR4) remain the major coreceptors used by the human immunodeficiency virus type 1 (HIV-1). In this study, we used an envelope-mediated fusion assay to demonstrate low CCR4 coreceptor activity with some primary HIV-1 and simian immunodeficiency virus-1 (mac316) isolates in vitro. The coreceptor activity was sensitive to CCR4-specific antibodies and to the CCR4-specific chemokine ligand macrophage-derived chemokine (MDC)/chemokine ligand 22 (CCL22). Treatment of peripheral blood mononuclear cells (PBMCs; which express high levels of CCR4) with CCL22 caused down-modulation of endogenous CCR4 but had no significant effect on HIV-1 entry, suggesting that CCR4 may not be used as an entry coreceptor. Despite expression of other minor coreceptors on PBMCs, CCR5 and CXCR4 are preferentially used by HIV-1 isolates, as shown by chemokine-inhibition data. To determine the factors involved in this selective use, we analyzed CCR4 coreceptor activity and compared it with CCR5 use in PBMCs. We used a quantitative fluorescence-activated cell-sorting assay to estimate the numbers of CCR4 and CCR5 antibody-binding sites (ABS) on PBMCs. Although CCR4 was found on a higher percentage of CD4(+) cells, CCR5 ABS was twofold greater than CCR4 ABS on CD4(+) cells. Confocal microscopy revealed strong cell-surface CD4/CCR5 but weak CD4/CCR4 colocalization in PBMCs. Binding studies demonstrated that soluble gp120 had greater affinity to CCR5 than CCR4. The results suggested that coreceptor density, colocalization with CD4, and affinity of the viral gp120 to the coreceptor may determine preferential coreceptor use by HIV-1.
尽管许多趋化因子受体在体外显示出共受体活性，但趋化因子受体5（CCR5）和CXC趋化因子受体4（CXCR4）仍然是1型人类免疫缺陷病毒（HIV-1）使用的主要共受体。在本研究中，我们使用包膜介导的融合试验来证明某些原发性HIV-1和猿猴免疫缺陷病毒-1（mac316）分离株在体外具有低CCR4共受体活性。该共受体活性对CCR4特异性抗体和CCR4特异性趋化因子配体巨噬细胞衍生趋化因子（MDC）/趋化因子配体22（CCL22）敏感。用CCL22处理外周血单核细胞（PBMC；其表达高水平的CCR4）导致内源性CCR4的下调，但对HIV-1进入没有显著影响，这表明CCR4可能不被用作进入共受体。尽管PBMC上表达了其他次要共受体，但趋化因子抑制数据表明，HIV-1分离株优先使用CCR5和CXCR4。为了确定参与这种选择性使用的因素，我们分析了CCR4共受体活性，并将其与PBMC中CCR5的使用情况进行了比较。我们使用定量荧光激活细胞分选试验来估计PBMC上CCR4和CCR5抗体结合位点（ABS）的数量。尽管在更高比例的CD4(+)细胞上发现了CCR4，但CD4(+)细胞上的CCR5 ABS比CCR4 ABS多两倍。共聚焦显微镜显示PBMC中细胞表面CD4/CCR5共定位强烈，但CD4/CCR4共定位较弱。结合研究表明，可溶性gp120对CCR5的亲和力大于对CCR4的亲和力。结果表明，共受体密度、与CD4的共定位以及病毒gp120对共受体的亲和力可能决定HIV-1对共受体的优先使用。
